1. Field of the Invention
This invention relates to a spandex in which a mineral additive is dispersed. More particularly, the invention concerns such spandex wherein the mineral additive is a mixture of huntite and hydromagnesite. The spandex of the invention has in combination decreased tackiness, increased resistance to chlorine-induced degradation, good operating continuity in dry spinning and satisfactory retention of the mineral additive during scouring and dyeing operations.
2. Description of the Prior
Spandex is defined generically as a manufactured filament or fiber in which the fiber-forming substance is a long chain synthetic polymer composed of at least 85% by weight of a segmented polyurethane. Usually spandex yarns are very elastic, but spandex yarns are also quite tacky compared to conventional "hard" fibers, such as of nylon or of polyester. The physical properties of spandex also are known to be detrimentally affected by exposure to chlorinated water, as for example in swimming pools.
Various methods have been suggested for ameliorating the problems associated with the high tackiness and low chlorine resistance of spandex elastic yarns. Some of the methods involve dispersing certain inorganic pigments in the spandex. For example, Goodrich et al, PCT application publication WO94/29,499, discloses that in addition to employing lubricating oils on the surface of the spandex, tackiness is further decreased by incorporating certain kinds of barium sulfate particles into the spandex. Martin, U.S. Pat. No. 4,340,527, discloses dispersing high purity, finely divided particles of zinc oxide in spandex to reduce chlorine-induced degradation. Dispersion of various carbonates, silicates, sulfates and oxides of group IIA metals in spandex is disclosed by Imai et al, U.S. Pat. No. 4,525,420, to improve the resistance of spandex to chlorine-induced deterioration. Japanese Patent Application Publication No. 59-133248 (Morifuji et al) and European Patent Application 0 489 395 (Ido et al) disclose that addition of oxides or hydroxides of magnesium, zinc or aluminum or hydrocalcite compounds of Mg.sub.x Al.sub.y (OH).sub.2 to spandex improves the resistance of the spandex to chlorine-induced deterioration. The incorporation of various inorganic particles into spandex as pigments or delustering agents is disclosed in Bell et al, U.S. Pat. No. 3,389,942.
Although the incorporation of the aforementioned inorganic particles into spandex is disclosed to provide certain positive effects, the particles also often cause certain problems. For example, the particles can plug filters and screens required in dry-spinning of the spandex and result in excessive interruptions in spinning continuity. Also, when incorporated in the spandex, the abrasiveness of the particles can cause excessive wear in parts of equipment typically used to incorporate spandex into fabric, for example, guides and knitting neeedles. In addition, some of the particles can be leached or extracted from the spandex by conventional acid scouring and dyeing operations and result in unwanted chemicals entering the effluent streams of textile plants as well as reduced effectiveness in the protection the particles were intended to provide. Accordingly, it is an object of the present invention is to provide a suitable additive for spandex that would avoid the above-recited shortcomings and still provide the spandex with decreased tackiness and increased resistance to chlorine-induced degradation.